Content in some text widgets are not visible

[calixteman]

Attach (recommended) or Link to PDF file here:
formulairecerfa90nov00-1.pdf
or here: http://mdph.cotesdarmor.fr/pdf/formulaires/formulairecerfa90nov00.pdf

Configuration:

• Web browser and its version: Firefox nightly
• Operating system and its version: Windows 10 pro

Steps to reproduce the problem:

1. Go to page 2:
   
   Enter a number in each fields (the input is supposed to be a single number)
2. It's impossible to read what it has been entered, so it isn't possible to check that the inputs are correct and consequently the user will very likely use another pdf viewer.

What is the expected behavior? (add screenshot)

What went wrong? (add screenshot)

[Snuffleupagus]

The naive solution would be to just decrease the vertical padding to e.g. 1px in

pdf.js/web/annotation_layer_builder.css

Line 65 in 70fc30d

padding: 0 3px;

However, without running tests I suppose that could break other things and we may perhaps need to limit that to only textWidgetAnnotation-elements and/or even just "short" fields!?

[calixteman]

And very likely, at some point, in a particular case, 3px was a good value so setting it to 1px will fix this issue and likely will break another pdf.
For a "normal" text field I don't really see the point to have this padding or maybe it is only useful for comb fields.

[Snuffleupagus]

Given that this issue seems to be (somewhat of) a special-case, how about simply using a CSS-class to set the padding to e.g. padding: 0 1px; specifically for textWidgetAnnotation-inputs where the width is e.g. shorter than ~15 pixels?
That should be a very targeted fix, thus reducing the risk of regressing anything else in the process.

[calixteman]

@timvandermeij, do you have an idea on what could be a good solution ? and maybe you could remember why you chose this 3.
Anyway I'm fine with @Snuffleupagus' solution.

[timvandermeij]

I see that I introduced the 3px value in e686db2. Back then we didn't have the associated test yet, but I did add that later and I recall having used the same document for the development of this patch, so I'd say if https://github.com/mozilla/pdf.js/blob/master/test/pdfs/annotation-text-widget.pdf still renders correctly (i.e., very similar to Adobe Reader) then changing the 3px should be fine.